ABSTRACT
With the advance of biotechnology, genotyping of a huge number of densely distributed genetic markers becomes cheap and fast. Single nucleotide polymorphisms (SNPs), which are tens or hundreds of thousands in number, are typical genetic markers. Since the markers are densely distributed, they present in the vicinity of any loci such as QTLs. When a marker is close to a QTL, the recombination fraction r between them is close to zero. Thus the genotypes of the marker and the QTL are simultaneously either homozygous or heterozygous with a negligibly small chance of exception. Thus the markers in the vicinity of a QTL can be treated as surrogates of that QTL. The mapping of QTL can then be done through the mapping of those surrogate markers.
